


Once in a Blue Moon

by lexi_con



Category: Fire Emblem Series, Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Ambiguous worldbuilding, Anal Sex, Animal Ears, Bestiality, Demons, Fuck Or Die, Love Confessions, M/M, Mutual Pining, Oral Fixation, Oral Sex, Royalty, Shapeshifting, Werewolves, excessive drooling
Language: English
Status: Completed
Published: 2019-11-28
Updated: 2019-11-28
Packaged: 2021-02-26 05:35:16
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 9,234
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21588478
Author URL: https://archiveofourown.org/users/lexi_con/pseuds/lexi_con
Summary: Hoping to help Dimitri through a difficult time, Sylvain offers his body and ends up giving far more.
Relationships: Dimitri Alexandre Blaiddyd/Sylvain Jose Gautier
Comments: 12
Kudos: 171





	Once in a Blue Moon

**Author's Note:**

> This was meant to be a Halloween piece, but better late than never, is what I say.  
> I just love Dimivain and since it is a rarepair I will have to make all this content by myself, I can feel my power returning.  
> So please heed the tags. Dimitri will shift into a wolf monster later in the fic and if that and all that comes with with it is not your thing please turn around.  
> I hope you enjoy the story, it became much more story than I was planning at first haha. If you wanna hit me up with that Dimivain talk you can find me at @lexificlets on twitter  
> There’s also an illustration up! https://twitter.com/lexificlets/status/1200912178804477952?s=21

”I can’t believe you’re doing this.”

Sylvain only smiles at the disgusted tone. He knows it is to disguise the worry the short wind weasel hides behind his tough exterior.

”You don’t believe in a lot of things, Felix,” Sylvain snickers as he applies crimson pigments at the corner of his eyes. 

The big eyes that stare back at him from the mirror are not his own, they are an illusion, along with the rest of his delicate appearance. Instead of muscles there are soft curves, chosen with care from Sylvain’s extensive visual library. The hair on top of his head is still his natural colour, but the tresses are much longer, fit to be pulled and tangled by strong hands. His tail is hidden for convenience but his ears remains the same; he didn’t want to give rumors that a human had come into the realm of Faerghus after all. 

”Stop playing coy,” Felix scolds, ”don’t you want me to cut him down instead?”

Sylvain resists the snappy comeback to that, _as if Felix would even be able to_ , ”I’m doing this of my own will. Besides, he’ll soon find a proper mate.”

The words sting even when they come from his own mouth, but Sylvain hides it with the black he applies to his lashes. 

”Who would be crazy enough to have that boar as their mate?” Felix grumbles disdainfully. Sylvain doesn’t have time to laugh with self deprecation before the doors to his chambers within the palace opens and an entourage of women come inside. They are all carrying something, save for Mercedes who leads the pack. 

”We came to dress you, Sylvain,” she says, voice as calm and serene as always, but a shadow of worry looms over her expression. 

Annette bounds up next to her, jewellery box in hand, ”wow, you did great with the makeup!”

Felix clicks his tongue at the compliment but says nothing, unwilling to show his temper to the harpy. Sylvain thanks them and undresses his feminine form to be decorated for the night. The clothes aren’t much for obvious reasons. A white yukata with slits up the sides for easy enough access and a simple blue sash tied around his waist. The fabric is of excellent quality though. Next are the jewels. 

Sylvain doesn’t move a muscle as earrings pierce his ears or when a veil weighs on his pointy ears to cover his hair and face. A collar clicks into place, tight around his throat. It is supposed to prevent a mating bond, but Sylvain wishes it off as soon as it touches him. But it isn’t his choice to make, so he quietly accepts the cuffs that wrap around his ankles to complete his preparations. 

As per tradition, the cuffs are chained together. Sylvain is not a mate, he is an aide, a temporary relief, a slave. They aren't cumbersome since there’s plenty of give for him to move still, but the symbolism is there. It doesn’t bother him, he’d gladly be a slave for the rest of his life, as long as he isn’t thrown aside.

”Are you ready?” Mercedes asks in that gentle way of hers.

”Of course,” Sylvain assures and follows when Mercedes leads the way. He waves goodbye to Felix who isn’t looking at him. That stings.

Outside his room Ingrid is waiting, spear in hand and wings folded neatly behind her. She doesn’t say anything, but the look she gives and then quickly turns away is enough. She accompanies them, to make it seem like a proper porcession, staying close to Sylvain in solidarity. 

They wander in silence through the palace, on display for anyone who might see them, but out of the way from the most crowded hallways. When they reach the stairs to the dungeons both Mercedes and Ingrid stop, knowing they shouldn’t go further. 

”Well, see you in a couple days, ladies,” Sylvain says as he proceeds to the stairs alone. He hears how Ingrid takes a wary breath, but says nothing. He doesn’t need her to. His role is clear, and he goes down the cold, damp stairs alone, only accompanied by the torches that line the curved wall. The echo of the chains seems much louder here, bouncing between the narrow walls as the chain around his feet hit new stone with every step he takes. 

When he comes around the last bend he sees Dedue, ever loyally guarding the door to the royal dungeon. His stern gaze doesn’t change when he sees Sylvain, but his eyebrows do raise by a fraction in surprise.

”How is he?” Sylvain asks before the large man can get a word out.

Dedue tries to school his expression, but he fails to hide the anxiousness completely when he glances over his shoulder, ”not good. For the moment he is calm, but he has been raging since early morning. He might be resting, so going in now would be the best opportunity.”

Sylvain nods, pushing past Dedue to lay his hand on the door. He feeds his intent into the seal that locks it and it dissipates without a sound. Sylvain turns to Dedue with a smile, ”go home for now, Ashe must miss you.”

”I cannot possibly–

”You can and you will,” Sylvain orders calmly, ”I doubt His Majesty would appreciate his closest retainer and friend listening in on this. Besides, I can handle him.”

Scepticism falls over Dedue’s face like a blanket, ”you do not truly know what he is like right now.”

”I don’t, but what will you do either way?” now there is a twinge of superiority in Sylvain’s tone, one he cannot stop. Dedue’s presence is merely a token at this point since no one can get in or out of the chamber without the proper intent. Interrupting what was about to take place was not one of the granted entries. 

Dedue knows this but seems unwilling to accept it. Not so surprising since he is so used to always be at the beck and call of his liege, but for a couple of nights that duty would befall Sylvain.

”I am serious Dedue. Go home. I will care for His Majesty.”

It is with finality Sylvain says it, because as he finishes he opens the door and steps inside the barrier that cuts him off from the outside world. It is only he and one other now.

The first thing he notices is the chaos of the large, circular room. What was left of a bed lay in shatters to the left, stripped of all the covers and pillows that should have been there. The room was originally decorated by caring hands, but now many of the fabrics and decor that presumably covered the walls were torn down, collected in the far side of the room. The mountain of cloth was impressive and as the door slammed shut behind Sylvain it stirred.

Heart beating in his chest, Sylvain watches keenly as a figure emerges from the blankets and pillows. The light hair of the monarch is a stark contrast against the black and blues of his fort, but it is obscured by his mantle and the large fur that is always draped over his shoulders.

”I was not to be disturbed.”

Sylvain feels a shiver run down his spine at the gravely, threatening tone. A strange mix of cold and warmth rushes over his skin in waves as he watches his king rise.

”I came to help,” Sylvain says, forgetting for a moment he was not here as himself, just a little surprised at his feminine voice.

The atmosphere is oppressing, but is becomes downright heavy when glowing blue eyes land on his form. Sylvain had seen his king angry and swallowed by his hatred and ghosts of the past, but never had he seen such disgust.

”Help?” the king repeats, turning to Sylvain, taking one heavy step at a time towards him, ”you do not even know what I _need_ . How would a dirty whore like _you_ be able to help _me?”_

With every word the distance between them lessens and Sylvain resists the urge to press against the door behind him when he gets trapped by the looming figure. The air smells of his dislike, his irritation, but most of all the scent of _sex_ intrudes Sylvain’s senses, making his knees buckle slightly. The king stands so close, naked apart from his mantle and Sylvain has to will himself to not let his gaze fall. A steadying breath will do nothing in this situation, so Sylvain has to lean against the door behind him to keep upright as the king’s aroma gradually fills him to the brim.

”I may not know everything you need, but I am here at your disposal,” Sylvain takes a deep breath, almost moaning as he gets another lungful of pheromones, ”you may do anything you want with me, Your Majesty.”

An arm slams against the door and Sylvain feels the way the barrier trembles from the force of it, but he refuses to look away from that brilliant sapphire that is staring down at him.

”I do not care, _you are not what I need_ ,” the words cut deep, deeper than they should, but Sylvain refuses to budge.

”Then tell me, what do you need?” he asks, fists clenching in the fabric at his sides, ”tell me, and I will do what I can to fulfill your wish.”

”How? By changing your form? _Worthless_ ,” the word is spat with such force Sylvain can feel droplets of spit land on his face, but he’s unbothered compared to the pain within him, ”if it isn’t real I do not care for it. I have spent far too long gazing at illusions.”

Sylvain’s heart aches at the confession. He considers dropping his altered form, but at the same time he is afraid what that would lead to. He could handle rejection like this, but if his king– _if Dimitri_ –would so bluntly reject him even in his true form he’d break. 

Words elude him, but action doesn’t. Without hesitation Sylvain sheds the semi opaque veil to present his current form fully, hoping he’d be able to calm the anger that has taken the kings reasoning hostage. As he tries to think of an argument that won’t make him seem like a desperate whore he feels a slight touch at his shoulder. A tress of his hair is pulled forward by the king’s hand, held there, studied.

”...the same,” the murmur is almost too quiet to hear.

Sylvain hears, but he doesn’t know what to do with those words, so he waits. Shivers exchange each other along his body as the king’s fingers combs through his hair, gathering more and more of it in his palm. Sylvain expects that fingers will clench around the strands at any moment to roughly yank him to the floor, but no such act happens. Instead, the king lifts his hand, bringing it up to his face, presses his nose into it.

_Oh no._

The thought of disguising his scent hadn’t crossed Sylvain’s mind, not when he had been bathed in oils and perfumed baths before he got dressed. Perhaps the king won’t be able to tell with the many floral scents covering his own, but he was also born with a keen nose, one that wasn’t easy to fool.

The answer comes all too soon, it only takes a moment for the king to open his eyes in shock, eyebrows raised in puzzlement as he studies Sylvain’s female form.

”Sylvain?” the whisper is rough, breathy. 

Sylvain’s gaze falls as he nods, seeing the king’s body tense. 

”N-no, no, nonono _nono!”_ the king hisses as he backs away, letting go of Sylvains hair in favour of wrapping his mantle closer around himself. The air becomes pungent with panic, but also arousal. Ah, a wave must have come at an untimely moment, that’s why His Majesty is so adamantly increasing the distance between them. It is the only thing Sylvain can tell himself to keep from falling apart.

The jig is up, and while Sylvain fears the harsh judgement that awaits him if he drops the illusion...he has to. The king deserves to see the truth.

But he isn’t looking as the deception falls away, revealing Sylvain’s true form. The king stands unsteadily, gripping his fur as if that was a better defence than his own legendary strength. He’s quivering beneath the black and white, hunched in on himself as if he is ashamed.

”Your Majesty,” Sylvain says as he moves forward, hoping to placate the wary king, ”please, I am here to help you. Tell me what I can do.”

”I-I...no, not you…anyone but you!” the king hisses and Sylvain feels the rejection as if it had punched him in the gut, stealing all his air, ”don’t come near me!”

But it is too late for that, Sylvain is already next to him, arm extending to gently lay a hand on the king’s trembling shoulder. ”I am sorry that I cannot be what you want, but,” Sylvain’s apology is cut short, air caught in his throat when piercing blue meets his own eyes. The king straighten his back, looming over Sylvain in the strangest mix of frightening and arousing. 

”Not like this,” the king mumbles, hand reaching up, cupping Sylvain’s jaw, ”I do not want it like this.”

Puzzled, Sylvain cocks his head to the side, pushing ever so slightly into the cold hand that holds him, ”what is it that you want?”

The king does not falter as he utters one, single word.

”You.”

Sylvain stares incredulously at the king, not registering the meaning behind that word. Him? What for? To beat up because he is so constantly a headache for the king and his court? Sylvain would like to think he makes up for his shenanigans by being the best diplomat and paperpusher in the country, along with being a decent fighter.

”Me?” Sylvain has to ask. He refuses to let the burning happiness and hope in the back of his emotional spectrum overtake him. Surely the king does not mean it the way Sylvain wishes him to. 

”The thought of _you_ has been the only thing grounding me through this hellish rut,” the king confesses, ”and the greatest frustration because you have not been _here_.”

Slowly the point is driven home, but Sylvain isn’t ready to accept it, afraid that he misunderstands, ”you said anyone but me.”

The king laughs, but it is a weary, empty one, ”I will soon lose my reason again and then I will act on instinct alone. I will hurt you, and I will not even remember doing it.”

”That is fine,” Sylvain says and raises his chin, exposing his jewelled throat, ”my life is yours.” 

A low rumble, a barely suppressed growl, comes from the king then as his eyes train at the decorated skin, "I do not want your life. I want your heart."

A sharp breath fills Sylvain's lungs and it is like he sees clearly for the first time ever. The king does not falter, gaze steadily locked to Sylvain's. Not a single lie can be found in those eyes and Sylvain wants to answer in kind. He takes the large hand that cups his jaw, urging it down to his chest. He presses there, ears flat against his head in a show of submission. "You have had it, for many years now," Sylvain confesses, choosing to lay himself bare in hopes that His Majesty would accept him.

The intensity and hostility falls from the king's entire frame and for the first time that night Sylvain can see _Dimitri._ He seems shocked, a little lost, almost innocent with how his cheeks go pink and eyes going shiny. It is a view Sylvain hasn't seen in so long, but he is happy he could be the one to bring it about again. 

While Dimitri still stands dumbfounded, struggling to find a response, Sylvain goes forward the short distance that separates them and raise to his tippy toes in order to place his lips on the other's. It is a quick peck, but the effect is immediate. 

Dimitri's entire face is blooming red when he realized what had happened, but he doesn't back away. Instead the amazed twinkle in his eyes is exchanged for an intrigued one, curiosity giving him an almost childish appearance despite his large body and muscles. Sylvain feels the corners of his mouth tug up in a barely contained smile of amusement. Why Felix insisted on comparing the king to a boar Sylvain had trouble understanding, he was much more puppy-like. Fitting, considering his species.

"C-can I kiss you?" Dimitri asks nervously, as if he would be rejected. Sylvain doesn't give him a reply, at least not verbally. Instead he grabs the fur that the king wears over his shoulders and pulls him close, pressing their mouths together once more in a desperate, hungry kiss. 

Decades of suppressed desire comes flooding out of the door Sylvain had locked it behind. His lips burn from the difference in heat between them but he doesn't mind. Instead he lets that consume him as he takes a deep breath, allowing himself to take in the smell of arousal from Dimitri.

The king is only frozen for a second before he sinks into the kiss, his arms circling around Sylvain to pull them flush against each other. He moans when his erection presses against Sylvain's hip and the fox responds in kind by grinding his lower body back and forth, making his own arousal obvious. Dimitri lets him, pleased hums and moans slipping out whenever their filthy mouths parted for brief moments. Their breaths become more ragged, neither wanting to pause their lips, their _tongues_.

Sylvain wraps his arms around Dimitri's neck, lifting himself those few centimeters that's missing between them, aided by the thigh that comes forward to press in between his legs. He balances on his tippy toes, but it is really the king that holds him up as they kiss again. This time Sylvain flinches a little as their fangs clack together and with each passing moment he feels the arms around him holding tighter and tighter, the hands that grip at his sides start to dig into his skin through his thin clothes. Soon the air is being squeezed out of his lungs and Sylvain has to break away to gasp for breath.

"Y-your Majesty," Sylvain warns, nudging at the king's arms. Immediately Dimitri releases him and takes one quick step back, almost as if he had been burnt and Sylvain nearly falls over when the support disappears.

Dimitri's eyes has taken on a wild quality, his pupils are dilated, but Sylvain can see the slight edge to them that signals instincts taking over. The king looks horrified at himself, hands coming up to cover his mouth and nose, as if that is going to help.

Sylvain steps forward, reaching out to put a gentle hand on Dimitri's head, "it is alright. I'm stronger than you seem to think."

The king looks sceptical, but he doesn't resist when Sylvain pries his hands from his face, revealing the sharp teeth that has grown in his mouth. He guides the other’s hands down, one to his thigh and the other to his ass, making sure they stay there even as the king blushes at the mere contact.

"If you want to squeeze, make sure you do it where there's meat," Sylvain encourages his words by shifting, making it easier for the other to grab him if he wants to. 

"I don't…" Dimitri swallows audibly and visually, trying to keep himself reined in, "want to hurt you."

All this hesitation is rubbing the fox the wrong way. Here he has laid his heart bare, dressed in ceremonial mating robes and kissed the other silly, yet the blonde idiot still won't accept him. Sylvain growls in annoyance at this, taking his king by surprise, "I'm not that weak, Your Majesty, so stop running away from me or try to make excuses. I came here to have you fuck me and it is going to happen whether you fight it or not.”

Dimitri's entire body trembles, his fingers twitch around Sylvain's thigh and ass. His will is breaking piece by piece but it is too slow, so Sylvain decides to speed up the process. He lowers his lashes, lets his tongue wet his lips and presses his palm against the king’s erection, moaning when he feels the dribbling precum wet his fingers. ”Why not make the first time you sink into my _tight_ ass something you can remember?"

A sound that’s a strange mix between a snarl and a moan is the only warning Sylvain gets before he’s hoisted up over the king’s shoulder and hurriedly carried and thrown into the bedding the king had been resting in before. The landing isn’t soft, but it doesn’t hurt either with the many pillows that are gathered. But Sylvain has no time to reflect on that when he’s covered, caged, by the man that comes to his knees above him. The mantle falls around them like a curtain and Sylvain twitches when his senses are assaulted by his king’s scent, all his frustration, arousal and evidence of release is so much stronger here in the nest. Goodness, it smells _divine_ and Sylvain almost cums from the scent alone, but he holds back, barely holding on to his thoughts. 

”Your Majesty…” Sylvain pants as he fumbles with the sash that’s tying his robe together, ”a-anything, do anything you want with me!”

The king rumbles in approval and instead of waiting for the knot to be untied he just rips the sash apart in a show of strength that has Sylvain’s breath catch in his throat. Large hands pulls his robe open, revealing the skin beneath to their touch. Sylvain shivers when the cold fingers cups his waist, but as they trace and press against his hipbones the shivers take on a more pleasant quality. A moan escapes him when blunt nails scrape through the hairs at the base of his cock and his hips twitch in an effort to get _more_.

”Still,” Dimitri orders with a heavy breath, pushing and holding Sylvain’s pelvic down. With effort that makes his legs quiver, Sylvain obeys, watching in impatient silence as the king observes the way his fingers move through the coarse hair. Slowly his hand moves just that little bit lower that it needs and his thumbs brush against the base of Sylvain’s cock. He tries to hump again out of instinct but the king holds him down, his impressive strength enough to keep Sylvain in his place without effort. Despite that, or maybe because of it, precum beads at the head of his dick and dribbles down his length. He’s entirely at the king’s mercy and nothing makes it clearer than the hungry gaze that observes the proof of his arousal.

Dimitri takes a deep breath, rumbling in the back of his throat before his hands go to Sylvain’s inner thighs, pushing them further apart as he leans down with his drooling mouth open.

Drops of saliva falls on Sylvain’s skin before Dimitri’s wet mouth wraps around him, lips sealing tight as he sinks down to the hilt, swallowing around Sylvain’s cock. 

”Oh my—,” Sylvain cuts himself off with a whine when Dimitri swallows again, mouth so obscenely wet, warm and tongue pressing hard against the underside of Sylvain’s cock. He wants to close his legs, squeeze them around the blonde head that is between them but he’s powerless against the king’s hands. He wants so desperately to hold onto those blond locks, but he doesn’t dare to take that step on his own. Instead he grips whatever fabric is beneath his palms, desperately trying to hold himself back as he twitches and squirms. But Dimitri is relentless, bobbing his head leisurely, making sure he touches every inch with his tongue, sucking greedily with every movement he makes.

There is no finesse or technique with the king’s actions, only hunger. Hunger for Sylvain and it is that more than anything that makes the pleasure overflow. 

”Y-your Majesty!” Sylvain arches off the pillows when his orgasm hits, his entire body trembling and tense with the onslaught of pleasure. He moans and cries as Dimitri eagerly swallows his cum, tears slipping from his eyes from the sheer force of the overstimulation. 

Laying as a fragile, twitching mess is what finally makes the king pull away, but only enough to let Sylvain’s softening cock slip out of his mouth. There’s still hunger, _lust_ , in his brilliant eyes and having that gaze directed at him has Sylvain jerking with another sudden aftershock of pleasure that almost scares him. 

Dimitri has a satisfied smile on his lips, like a dog that knows it has done a good job as he sticks his tongue out to lick at the excess saliva that dripped down Sylvain’s balls.

“W-wait, Your Majesty…” the stimulation is too much and with the hands that still holds his legs open only words and his own hands can be used to try and beg for some respite from the king’s mouth, “t-too much.”

Dimitri pauses. His mouth is wrapped around one of Sylvain’s balls, tongue pressing it to his palate even as he stills. He doesn’t seem overly concerned with Sylvain’s dilemma, but frees his mouth to say, “call my name.”

The king’s name has so many times been on his tongue in his most private moments that it is almost embarrassing to say it now. His blush must be in awful contrast to his ginger hair, but he can't help it when the king looks at him with such anticipation.

Sylvain folds his ears down in embarrassment and covers his face, unable to look into those sincere eyes that watch him so intently. 

“Dimitri…” Sylvain whispers, voice high and pathetically shaky for such a simple task.

”Let me see you,” Dimitri says, grabbing Sylvain’s arm and jerking it away, crumbling Sylvain’s defenses effortlessly. The king seems satisfied, smiling as he drags himself up and over Sylvain’s body again, having Sylvain straddle his hips and feel his large cock drip precum over his stomach. 

Their lips meet again in a slow, sloppy kiss where Dimitri eagerly sucks on Sylvain’s tongue, making him taste the tang of his own release. He doesn’t protest, instead encouraging the king to do as he likes, take what he wants. Sylvain traces his foot up along the king’s leg, spreading himself more, inviting. Arms wrap around Dimitri’s shoulders, holding him close, gentle fingers making soothing circles against his skin under the mantle. 

The king moans into Sylvain’s mouth, lips and tongue growing more frantic along the way Sylvain grinds against his body in small, seductive movements. 

”Sylvain…” Dimitri mumbles when he breaks their lip-lock only to trace his mouth down Sylvain’s neck, grunting as his lips reach the jewelled collar that hinders the king from placing his claim. He tries to rip it apart with his teeth, but the many pearls and jewels won’t tear in their bindings even when the king tries to use his hand to take it off. 

”Remove it,” Dimitri orders, but he sounds childishly dejected that he can’t do it himself.

Sylvain has to giggle a little at the almost pout the king has on his face, ”can’t. Mercedes put it on.”

The sudden snarl he gets as response takes Sylvain aback. His heart leaps in his chest when the king surges up and flashes his teeth in irritation.

”Don’t take someone else’s name in your mouth when you’re with me,” Dimitri threatens, voice dark with something akin to jealousy, ”you’re mine now.”

Sylvain whines at those words. His entire body gets rushed with pleasure that makes him feel tense and relaxed all at the same time. He is powerless to do much more than cling tighter around the king, body begging for those words to be put into action.

”I am,” Sylvain moans and can’t help it when he lifts his chin to show off his neck once again, instinct telling him to yield all of himself to the man above him, ”I’m yours, Dimitri.”

Despite his outburst, the king seems almost surprised when Sylvain agrees so readily. But the shock only lasts for a moment before the king leans down, teeth and tongue scraping along the edges of the choker to put temporary marks that wouldn’t fade until he could put a proper mark on the skin. 

Along with the insistent markings with his mouth the king also reaches down and cups Sylvain’s ass, pulling him upwards and pressing their hips together further, rocking them. Sylvain moans and hooks his leg around Dimitri’s thigh, pressing in even harder. He’s growing hard again, the king’s saliva and precum mixing on his stomach to make a filthy lube, easing their movements against each other. At first the king is satisfied with the rock and grind, but soon his hips moves in bigger motions, back curling with every thrust he makes against Sylvain. His warm breath grows heavy against Sylvain’s neck. Ragged, not unlike a beast.

”Dimitri,” Sylvain manages to moan out as he pushes at the other to look at him. With seemingly great effort Dimitri pulls away from the band of possesive bruises he’d left just beneath Sylvain’s jaw so their eyes can meet. His pupils are slitted, proof that he soon won’t be able to resist the blue full moon and its influence on his body. 

Sylvain tries to smile reassuringly, brushing some of the blonde tresses in the king’s hair out of his face, getting a proper look at those hungry, _lusting_ eyes. ”Do you want to be inside me?” Sylvain asks, intently watching how the king swallows heavily and nods.

”Then you can,” Sylvain relaxes himself, giving the king ample room to move. A slick sound makes Sylvain look down at the mess they’ve made on his stomach and now _he’s_ the one that has to swallow when he sees Dimitri’s stiff, large cock covered in their combined juices. 

Sylvain shivers when a fat drop of precum falls onto his own dick when Dimitri pulls back to reposition himself, it would be a nice extra lube, even if Sylvain made sure he was properly oiled up before coming here. 

When he feels the hot head pushing against his hole he digs his nails into Dimitri’s shoulders, stomach knotting in nervousness and excitement. His body yields easily when Dimitri pushes forward, their voices overtaking each other as they moan in unison. The king visibly tries to hold himself back, to go slow, brows knitted in concentration. While his discipline is admirable, Sylvain knows they do not have time for slow and sweet before the king loses his reason. So, unflinching, he wraps his legs around Dimitri’s thighs and _squeeze_.

Sylvain arches his back as he’s filled, feeling the full girth and length of the king stretching him to his limit, moans at the thought that finally, _finally_ —

” _Sylvain_!” Dimitri whines, entire body shaking as he watches Sylvain writhe and rock his hips back and forth beneath him. 

Sylvain gasps for breath, struggling to accommodate the king’s large cock inside him. He has to take several deep breaths before he can nod, giving the king his permission to move. 

A deep, satisfied grumble leaves the king, his expression changing from surprise and pleasure to something much closer to determination as he leans forward again, silently ordering Sylvain to open his mouth. Complying without question, Sylvain moans when Dimitri pushes his tongue past his lips, ever so slowly matching the movements of his hips and tongue. 

Sylvain’s eyes roll back from the pleasurable actions, letting himself sink into the pillows and enjoy the attention the king is giving him. He has his hands that rested on Dimitri’s shoulders slide down his sides, taking care to feel the strong muscles under his touch at every thrust. He’s still careful with his movements, completely unnecessary, and Sylvain digs his nails into the king’s asscheeks, trying to force him to move _harder_.

The king groans into Sylvain’s mouth, his own hand finding its way into Sylvain’s hair and to the base of his ear. Surprised, Sylvain hisses into the kiss, but from the moan he gets to swallow his sudden tension wasn’t unpleasant. But he has no time to think about that, not when calloused fingers scratch against his sensitive ears. It is too much, everything is _too much_ and he wants to break from the kiss but finds himself unable to do so, unable to resist anything Dimitri does to him. 

Frantically he scratches his nails up along Dimitri’s back, surely with enough force to leave more than marred marks. His hands struggle to find something, _anything_ , to hold onto, to anchor himself on the waves of bliss that overtake him with every movement the king does. But Dimitri refuses to slow down, or maybe he’s lacking the presence of mind to realize he is just _too much_ , and reaches between them to wrap his hand around Sylvain’s cock. The slick that coats his cock makes the slide of Dimitri’s palm against him far too easy, far too good. Sylvain bounces his ass in desperation, toes curling as orgasm hits him with violent force, making him shoot his cum all over his stomach and the king’s hand.

” _Mnnmgh—!”_ The cry is muffled and greedily taken by Dimitri’s mouth, and Sylvain spasms with every movement the king makes with his hand, milking Sylvain of every last drop of his cum. Dimitri is merciless, edging the pleasure into pain with his insistent hands and strong thrusts. Sylvain tries to ease his hand away, but the king merely growls in dismay and refuses to let go. 

Desperate for some kind of pause, Sylvain bites down with his fang on the king’s tongue who yelps in pain and jerks back. He seems irritated at the action, but when he tries to move in again Sylvain makes a show of turning his face away. 

”No,” Sylvain flatly tells him, but Dimitri doesn’t seem to pay it much mind until Sylvain swats his hand away from his spent dick and flashes his teeth in warning, ”I said _no_.”

Shocked, the king stills fully. He’s almost panicked at the interruption, but his eyes are clear enough that Sylvain knows he is listening. Sylvain takes a second to readjust himself and calm his frayed nerve endings before he opens his mouth.

”I appreciate your eagerness, but you don’t need to rush,” he says and runs a soothing hand up Dimitri’s arm.

Dimitri blinks down at him, seemingly puzzled by the words. 

Sylvain lets his hands follow the muscles in Dimitri’s arms up, over his shoulders and around his jaw, cupping it tenderly, ”this won’t be the last time you’ll have me Dimitri. I’m not going to disappear.”

Blue eyes brighten in realization, softening with tears as Dimitri gently collapses down, laying himself over Sylvain, nose tucked into red locks and mouth leaving apologetic kisses to the edge of Sylvain’s jaw. 

Sylvain smiles and cradles Dimitri against him, one arm wrapping around his back and the other going to his hair to let his fingers comb through the king’s blonde hair soothingly. ”It’s alright, Dimitri,” Sylvain mumbles, ”it wasn’t _bad_ , just a little too much.”

Another sorry whine comes from the king as he seeks forgiveness. Sylvain can feel that he’s still hard inside of him, and the slight trembles he feels are probably not just from the reprimand. 

”Come on,” Sylvain ushers, rolling his hips in a way he thinks is enticing to get the king back in the mood, ”don’t you want to cum too?”

Dimitri makes a tiny nod, but he holds Sylvain tighter, one arm snaking beneath the arch of Sylvain’s back and tightening there. He makes a small rocking movement and Sylvain sighs softly to assure him that is alright, that he is free to move. 

The king doesn’t lift his head, only alternating his attention between Sylvain’s hair and shoulder as his hips grows more frantic, chasing his own release. He grunts and moans, broken whispers of Sylvain’s name leaving his mouth as he fucks into Sylvain’s warmth. Only their soft moans and the slap of slick skin against skin fills the air, sinking them into the pleasure they share. Sylvain isn’t hard yet, but every movement Dimitri does shoots a rush of dull pleasure up his spine that replaces the overstimulation.

The slow, careful thrusts gradually become stronger, faster. Dimitri’s open mouth leaves wet bites along Sylvain’s shoulder, his teeth gradually becoming sharper to leave deeper, lasting marks. It isn’t far off now, the transformation.

”You’re so good, Dimitri, holding yourself back for me” Sylvain moans as he combs Dimitri’s hair tenderly, ”but it’s alright, you can let go.”

Dimitri whines, hips shaking, snapping forward with force that leaves Sylvain crying out. Stubbornly Dimitri grinds into Sylvain as he comes, moans mixing with growls and snarls like that of a beast. He seems desperate to get closer, desperate to fill every inch of Sylvain’s insides with his seed, to mark every part of Sylvain as _his_.

Sylvain feels as if something inside him breaks when the king pumps him full of his cum. His body sings in satisfaction, almost as if it was begging for the king to breed him, begging to be impregnated even if it was impossible. His mind is blank, no coherent thought forms even as he tries, only instinct telling him that he has to keep the other close.

”S-Sylvain,” Dimitri rasps, voice barely recognizable. Sylvain gasps when a rough, inhuman tongue licks across the mounds in his shoulder, fingers gripping around fur instead of digging into skin. The arm that was wrapped around his waist disappears, giving him the chance to observe what was happening. He’s seen it before, but never this close, this intimately.

The hands that held Sylvain close with gentle force changes their grip, nails growing into claws and almost piercing skin before the king let go, forced to straighten his arms as the bones inside them crack and change. Black fur grows rapidly around Dimitri’s neck and shoulder and when his entire head is covered this features change completely. His nose grows into a long snout and his teeth that had already become uneven transforms into jagged tips that could easily tear flesh from bones. He growls in pain when two large tusks grows from the base of his jaw and throws his head back and forth as horns sprout from behind his ears.

As his head transforms into what can only be described as something wolf-like the rest of his body changes as well. His shoulders become more muscled and his mantle falls to the floor when there’s nothing for it to rest against anymore. Sylvain barely notices how the cock inside him slips out when Dimitri rolls his spine upwards, too transfixed on the change that is happening before him. He wants to reach out, to try and ease the pain that the king feels as his bones and skin stretch and contort to accommodate the shape his bloodline binds him to, but knows it would do no good.

The moment feels like it lasts for hours, but it hasn’t even been minutes when the sickening sound of the shift has stopped and the king’s ragged breath loses the suffering mewls. 

Awe and fear rush through Sylvain in a strange mix as he gazes up at the monstrous form of Dimitri, for the first time truly understanding the terrified screams of those the tempest king mauled on the battlefield. 

But this is not a battlefield and Sylvain isn’t an enemy, so he swallows thickly before reaching out, behind the curved tusks and holds the king’s head gently, careful of the suddenness of his action. Dimitri tenses for a split second, but when his nose twitches in small sniffs he relaxes again, realizing that it isn’t an enemy, that this isn’t a fight. He opens his eyes and Sylvain is taken in by the brilliant blue that shines with powerful magic just beneath the surface. 

”You’re beautiful, Dimitri,” Sylvain says honestly for lack of something more seductive, but he still feels the draft of a wagging tail close to his toes when the compliment registers. Surprised, Sylvain tears his gaze away from the other’s eyes and looks down between them, seeing a rather normal wolf’s tail swish back and forth. He’d never seen the king transformed without merging with his lance that gives him a much more deadly rear end. 

Though the black and white tail is far less noticeable than the dark pink cock that’s drooling with a filthy mix of semen and precum between his legs. Sylvain has to take a steadying breath when he sees it, his animalistic instincts reacting so very strongly to the view of the slick length. Arousal spreads underneath his skin like a wildfire when a primal voice whispers what that cock, what _Dimitri_ , will do to him, how it will utterly _ruin_ him.

Before he can stop himself a suppressed, desperate moan tears from his lungs and it snaps the king out of his post-shifting haze. Sylvain doesn’t protest when a cold nose settles on his burning skin, taking in his scent of arousal that must be so painfully obvious to Dimitri by now. The wet nose bumps against Sylvain’s nipple, making him twitch from the difference in temperature, only to have a wide, hot tongue replace the chill. 

The texture is unlike anything Sylvain has ever felt; rough with the miniscule bumps on the surface, yet gentle with the motion. He isn’t a cat so he doesn’t purr, but the sigh that he gives the king in approval is close enough. Though the sensation doesn’t last long as Dimitri swiftly moves on, lapping at the sheen of sweat that covered Sylvain’s chest and down, down to the drops of cum all over his stomach. 

The king laps at him like he’s a spring of water in a desert, greedily swallowing all of their mixed juices and making sure he doesn’t miss a single drop. The rough tough insistently pokes at Sylvain’s navel, convinced it must be hiding more, and Sylvain’s hips jerk with every forceful lick, the nerve leading down to his cock tickling him with pleasure every time. He’s hard again and he doesn’t know if he wants the king to notice or not, fearing he’d lose his mind if the long, eager tongue got a taste of him there. 

Though the answer never comes. Instead of moving down Dimitri uses his paw to push at Sylvain’s side, prompting him to roll over. Only now does Sylvain realize how much of his strength has zapped; simply turning to lie on his stomach is a difficult feat that leaves him gracelessly falling down onto the pillows again. His limbs are like jelly, but Dimtri doesn’t seem bothered. 

The robes still hide the upper part Sylvain’s back, but his lower body is conveniently bare and exposed. He arches in surprise when Dimitri’s snout trace down his spine, tasting the skin, feeling the dip of muscles. Further and further down he goes, to the cleft of his ass where the king’s cum has dribbled out. That broad, flat tongue cleans it away, thorough on the way down to the source where it pays extra attention to the quivering entrance. 

Sylvain moans each time the rough texture teases over his perineum and entrance, but it isn’t what he wants, not what his instincts tell him he _needs_. 

In a spur of the moment decision, Sylvain lets his tail come out and it flops down over the king’s head, between his horns. Surprised, Dimitri draws back and snarls in warning, probably thinking Sylvain is somehow trying to stop him when that couldn’t be further from the truth. 

Before the king can come at him again Sylvain quickly gets on his hands and knees, tail swept to the side to show off his ass fully. He looks back, giving Dimitri the most seductive look he can manage, imploring him to _get on with it_ . At first Dimitri tries to dive his nose back to resume his licking, but Sylvain immediately blocks him with his tail, trying to tell him that _no, not what I want_.

”Come on, Dimitri,” Sylvain huffs out in frustration when the king tries to satisfy his oral obsession once again, ”I’m flagging like a bitch, can’t you just get the damn hint and _fuck me_ already?”

As expected Dimitri doesn't recognize the words and becomes ever more irritated at Sylvain’s rejection, going as far as growling to threaten him into place. But they can be two at that game. 

Sylvain reaches back, looking the king straight in the eyes as his fingers feel their way through the slick drool all over his ass until he can plunge his fingers into himself, moaning heartily each time he pushes inside. It is a bit overdramatic, but as he goes Dimitri’s rumbling fades and he hears the heavy breathing return. Dimitri stands, wholly focused on the way Sylvain’s fingers fuck his own ass, tongue lolling in and out of his mouth as drool starts dripping.

”Yes, good boy,” Sylvain urges, craning his neck even further to catch a glimpse of the other’s stiff cock that’s dripping as much precum as his mouth drools. A current of arousal goes through Sylvain, seeing how that flushed cock twitches in interest each time he pushes his own fingers inside himself. He could cum like this, feeling the coil in his lower abdomen tensing more and more with each moment, each image of that large, slick cock inside him fueling the fire even more. 

”Please, Dimitri... _please!_ ” Sylvain whines, wanting so desperately to have it inside him, to feel the difference between this and what Dimitri was before, to get used and filled by a _beast._

As if heeding the plea, Dimitri moves forward, but this time his snout passes Sylvain’s ass after a quick, indulgent lick and climbs over him. The difference in size is almost frightening, Dimitri is so broad and Sylvain feels his muscles against his back as the king settles above him. He’s trapped in by strong legs that end in paws with sharp claws and teeth that are literally a breath away from his neck, but it feels so _right_ his mind can’t catch up to the fact that he’s completely at the king’s mercy. Or maybe he does, but he _likes it_. 

Without a moment's pause Sylvain removes his fingers from himself, instead reaching beneath where he can feel the heat of Dimitri’s cock radiating against his inner thighs. He drops his head, and lets out a broken, loud noise when he sees the king’s cock between his legs. The dark pink cock is both wider and longer than his own and he can’t stop the squirt of cum that escapes him when he truly, fully realizes it will be _inside, inside, inside!_

His fingers tremble as he reaches for the bobbing dick, skin so hot he almost thinks he burns the other when he wraps his fingers around the shaft and Dimitri jerks forward in a humping motion. Sylvain whimpers when he feels the strength the king rocks against him with, anguished over the fact that he’s not getting _fucked_ already. 

Groaning, Sylvain has to lay his head on the pillows, reaching back with his other hand as he lowers his hips to them, almost losing his coherent thinking when he feels Dimitri’s wet tip push against his perineum and balls. But that isn’t enough, it has to be—

His entire body jerks when Dimitri’s cock sinks into him, stretching him to his limit without a moment’s pause, only chasing pleasure. Sylvain doesn’t know if he moans, screams or can’t get a sound out; everything turns white and his ears ring with noise that he can’t process. His entire body burns in a mix of pain and pleasure as his hips stutter with orgasm, spilling obscenely all over the bedding. 

Nothing matters, nothing but the sweet stretch of his ass and the pleasure that Dimitri gives him and Sylvain makes no effort to try and stop him, too lost in the aftershocks of orgasm to even care what is being done to him. 

He thinks he feels something at his throat, but there’s only a brief shortage of breath before he falls into semi-consciousness again, only moaning breathily when he feels wet heat enveloping the nape of his neck. There’s pricks of pain, but they keep him in place and Sylvain can only pliantly go lax beneath the pressure as he takes whatever Dimitri gives him, offering whatever Dimitri wants.

The cock fucking him is the only think holding his ass up and Sylvain marvels at how good it feels to let go, to leave all control to his king, his _lover_ , and not be afraid of failing. Dimitri only needs him to stay still and obey every whim of the king. He can do that, he can be a convenient hole for his Dimitri to use as he wishes.

Suddenly there isn’t just a slick, effort less slide to the king’s movements anymore. Something at the base of his cock catches with every thrust, forcing Sylvain to think for a brief moment, to realize what is about to happen to him.

A knot, like every canine animal has. A knot that will lock them together, keeping the seed inside of him, to mark and shape his insides so he’d never be able to have anyone else ever again. 

_To ruin him._

Sylvain squeals in delight, some deep and twisted instinct telling him that with this, he will be Dimitri’s. _Forever._

He begs, with breathy words and broken sobs, for Dimitri to claim him, to take whatever he wants, to keep Sylvain as his own for all eternity. With each plea the knot grows larger, stretching Sylvain more than he ever thought he’d be capable of, until it slips into Sylvain’s hole, unable to pull out again. Dimitri slams his hips forward with a growl that softens to a whimper as he pumps his cum into Sylvain with eager, desperate rocking motions. 

Sylvain can’t tell if he cums again or if it is the heat of Dimitri’s release inside him, but pleasure rolls over his body like chills and he barely holds on to the world around him as his head swims in bliss. 

All he feels is Dimitri. The fur along his back, the warm breath and prickling pain against his neck; the knot and semen filling his insides up to the point of bursting. Everything. 

He isn’t sure how long he lays there, but eventually he can feel the knot inside him shrink, easing the pressure in his abdomen until it’s enough for Dimitri to slip out. Spent, and too thoroughly fucked to even try and gather any strength, Sylvain drops down. He feels an obscene amount of cum leak out of him and down over his balls, so sensitive even that light sensation is too much for his frayed nerves. 

He does manage to open his eyes though, seeing out of the corner how Dimitri pants above him, licking his lips and observing Sylvain now that he has been momentarily satisfied.

”Dimitri,” Sylvain slurs and with huge effort manages to turn onto his side. 

Dimitri looks down at him, something more than instinct and need reflecting in his eyes. Something more...tender softens the deep blue as he leans down. Sylvain obediently opens his lips, letting the other’s tongue lick inside his mouth in a weird imitation of a kiss. But it feels good, gentle, as if Dimitri is aware that he can’t be too demanding, needs to be careful now that he’s had his way. 

When Dimitri pulls away Sylvain has to swallow the excess saliva he’s been given, but doesn’t mind even as a heavy glop that connected his and Dimitri’s tongue fell onto his chin. Dogs drool when they see something they like, right?

Sylvain only has a second to inwardly snicker at his own joke and file it away for later when Dimitri’s paw pushes at his shoulder, helping him to turn fully onto his back. At first he thinks Dimitri wants to have himself another lick-down, but then his jaw opens wide as he lowers his head again, settling his teeth around Sylvain’s throat, gently biting down. Sylvain expects to feel nothing, the choker around his neck there to protect the skin beneath. But pain does register and Sylvain realizes he can’t feel the jewels and pearls against his skin anymore, only teeth and a wet, hot tongue.

Dimitri is marking him. 

Tears well up in Sylvain’s eyes as he realizes what’s happening. Through the punctures that Dimitri’s teeth leaves his life force will enter Sylvain’s body and in a few days the symbol of his family crest will appear at Sylvain’s throat. The ultimate claim.

A promise to be together, forever.

* * *

”Dimitri please, this is embarrassing.”

”But you can’t really walk right now?”

Why it is a question, Sylvain has no idea; His Royal Majesty knows full well what he has done to Sylvain and the effects it has had on his body. Still, he would be fine if he could just hold on to Dimitri’s arm, a princess carry was over the top.

”I am not a child,” Sylvain tries but Dimitri just looks confused.

”I don’t think of you as a child, I just want to take responsibility. It is my fault you ended up like this after all,” Dimitri is so genuine in his chivalrousness that Sylvain blushes for him.

”When did you learn to talk like that?” he accuses, not used to any kind of suave or flirty behaviour directed at himself, and definitely not from his crush. Turned lover. Turned unofficial husband.

Sylvain’s cheeks heat more as his hand touches his Adam’s apple. Dimitri’s smile widens and brightens like the sun as he sees Sylvain caress the mark that shows who he belongs to. Sylvain sees that as an invite to hook an arm around Dimitri’s neck and pull him down into a sweet kiss, chaste enough that it wouldn’t impair Dimitri’s ability to walk, but deep enough to have them both sigh in content.

”Fucking hell, put some clothes on!”

The angry shout bursts their bubble unceremoniously and both Sylvain and Dimitri manages to catch a glimpse of Felix as he storms down the corridor he probably came from, his disgusted curses mixed with comments that he’s thankful they are alive but not _that_ thankful. 

Sylvain vinces at the thought of whatever violent act Felix will perform in retaliation for seeing him nude but is secretly glad his old friend had been on his way to check up on them. 

”How long until the entire court knows about this?” Dimitri asks in good humor.

Sylvain laughs and lays his head against Dimitri’s shoulder, ”depends on where Annette is.”

  
  
  
  


**Author's Note:**

> I hope you enjoyed this story!  
> Plz leave a comment if you liked this, it is my lifeblood and feeds my Dimivain brain to make more Dimivain content for us all


End file.
